1. Field of the Invention
The present invention relates to an imaging apparatus and an endoscope, and particularly to a compact imaging apparatus in which electronic components and signal cables are connected to a bendable circuit board, and an endoscope.
2. Description of the Related Art
An endoscope includes an insertion section which is inserted into a body of a test subject, and an observation optical system configured by a lens and a prism is provided at a tip end portion of the insertion section. A solid state imaging element such as a CCD is provided at an image forming position of the observation optical system. The solid state imaging element is connected to a multicore cable through a flexible board with flexibility. Further, electronic components are mounted on the flexible board to drive the solid state imaging element. The multicore cable is electrically connected to a processor. Thereby, the observational image of a lesion portion or the like is formed on the imaging element through the observation optical system, and is subjected to photoelectric conversion, and then, the electric signal of it is properly subjected to signal processing by a processor, is output to a monitor TV, and the observational image is displayed on the monitor TV.
Incidentally, the tip end portion of the insertion section of an endoscope is desired to have a small diameter for the purpose of reduction in burden on a test subject. Therefore, the wiring module such as a board is desired to be compact (reduction in diameter/reduction in length, in concrete). Therefore, an increase in the elements on the circuit board, reduction in pitch of the pattern on the circuit board, reduction in diameter of a cable, and space saving of the cable connection part are required.
Further, since a sealing resin used in an endoscope not only satisfies the bonding strength and electric performance, but also needs to meet specifications for cleaning after use, the sealing resin is required to have water-tightness and air-tightness, and sealing needs to be performed with a minimum of voids.
Concerning resin sealing of the imaging apparatus for an endoscope, various proposals are made.
For example, Japanese Patent Application Laid-Open No. 05-207971 describes an endoscope in which an inside of a frame of an outer circumference is filled with a first resin for reinforcing the imaging apparatus, and a second resin for ensuring flexibility of the rear end portion of the imaging section.
Japanese Patent Application Laid-Open No. 2002-159438 describes an imaging unit for an endoscope in which a resin is injected and filled with high density by providing a frame for autoclave resistance.
Japanese Patent Application Laid-Open No. 2001-46323 describes an endoscope in which after sealing is performed with a fluorine rubber resin, its periphery is sealed with an epoxy resin with relatively high water absorptivity, and the epoxy resin is covered with a tube, for autoclave resistance.
Japanese Patent Application Laid-Open No. 2002-159439 describes an endoscope in which an inside of a frame or a heat-shrinkable tube, which is provided outside, is sealed with a first adhesive agent which ensures insulation, and an outside of the first resin is sealed with an adhesive agent with low steam permeability.
Japanese Patent Application Laid-Open No. 06-178757 describes an endoscope in which a flexible board mounted with electronic components is bent to have a steric structure, and the electronic components, a tip end portion of the flexible board and a cable connection part are sealed with a resin.